New Study Shows How
Exercise Lowers Cholesterol Risk

Need another reason to exercise? Scientists
have discovered it makes cholesterol less dangerous.

A new study found that even modest exercise
changes the size and density of cholesterol-carrying proteins so they do less
damage. And the benefits occur even if people's total amount of cholesterol and
their weight stay the same.

Staying active has many health benefits, but
improving cholesterol is not usually considered one of them. People who
exercise often lose weight, and while that can improve their cholesterol
levels, exercise by itself was thought to have little or no effect.

Workouts fail to lower LDL, the dangerous
form of cholesterol, and only rigorous exercise can nudge up HDL, the good form
that protects against heart attacks.

But the study, by Dr. William E. Kraus of
Duke University, found a new way that exercise can affect cholesterol  by
altering the number and size of the particles that carry cholesterol through
the bloodstream.

"People in the exercise field have always
wondered why it doesn't affect total cholesterol and LDL," Kraus said. "We
always knew low levels of exercise are helpful. This helps solve that
paradox."

His work, published in the New England
Journal of Medicine, is the latest chapter in an evolving view of
cholesterol's effects. A generation ago, doctors worried only about the total
amount of cholesterol. Later, the importance of the main subtypes, especially
HDL, became apparent. Now experts are turning their attention to the physical
structure of cholesterol in the bloodstream.

Cholesterol is an essential fat, or lipid.
It circulates through the body by attaching to protein particles. Cholesterol
appears more likely to clog the arteries when it is carried by small, dense
protein particles than when it is moved by relatively large, fluffy ones.

The latest study finds that people who
exercise develop these bigger particles, even if their total amount of
cholesterol stays the same.

"Using this analysis shows clearly that
exercise has beneficial effects that are not revealed by standard tests," said
Dr. Ronald M. Krauss of the Lawrence Berkeley National Laboratory, who studies
the protein particles.

The study, conducted at Duke and East
Carolina University, involved 111 sedentary, overweight men and women. They
were randomly assigned to three exercise groups: the equivalent of walking 12
miles a week, jogging 12 miles a week or jogging 20 miles a week. All were
instructed to eat enough to keep their weight constant.

They found that the cholesterol effects of
walking and jogging 12 miles were the same, while jogging 20 miles resulted in
more pronounced changes.

Measuring protein particle size is sometimes
done in large medical centers, but it is not part of standard physicals. Kraus
said he expects the tests, which cost two or three times more than standard
cholesterol tests, to become more widely used.

Dr. Joann Manson, head of preventive
medicine at Harvard's Brigham and Women's Hospital, noted that exercise has
already been found to have many other benefits for the heart, including
improvements in blood pressure, blood sugar, clotting and inflammation.

Studies show that briskly walking 30 minutes
a day can lower the risk of heart disease by 30% - 40%.

This article was prepared by Heart
Disease Weekly editors from staff and other reports. To see more of the
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